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  • Need help with this basic Contains<>() extension method and Lambda expressions

    - by Polaris878
    Hi, Say I have the following class: class Foo { // ctor etc here public string Bar { get; } } Now, I have a LinkedList of Foos declared like so: LinkedList<Foo> How would I write a basic Contains<() for this? I want to be able to do this: Foo foo = new Foo(someString); LinkedList<Foo> list = new LinkedList<foo>(); // Populate list with Foos bool contains = list.Contains<Foo>(foo, (x => foo.Bar == x.Bar)); Am I trying to do this correctly? Thanks

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  • I have written an SQL query but I want to optimize it [closed]

    - by ankit gupta
    is there any way to do this using minimum no of joins and select? 2 tables are involved in this operation transaction_pci_details and transaction SELECT t6.transaction_pci_details_id, t6.terminal_id, t6.transaction_no, t6.transaction_id, t6.transaction_type, t6.reversal_flag, t6.transmission_date_time, t6.retrivel_ref_no, t6.card_no,t6.card_type, t6.expires_on, t6.transaction_amount, t6.currency_code, t6.response_code, t6.action_code, t6.message_reason_code, t6.merchant_id, t6.auth_code, t6.actual_trans_amnt, t6.bal_card_amnt, t5.sales_person_id FROM TRANSACTION AS t5 INNER JOIN ( SELECT t4.transaction_pci_details_id, t4.terminal_id, t4.transaction_no, t4.transaction_id, t4.transaction_type, t4.reversal_flag, t4.transmission_date_time, t4.retrivel_ref_no, t4.card_no, t4.card_type, t4.expires_on, t4.transaction_amount, t4.currency_code, t4.response_code, t4.action_code, t3.message_reason_code, t4.merchant_id, t4.auth_code, t4.actual_trans_amnt, t4.bal_card_amnt FROM ( SELECT* FROM transaction_pci_details WHERE message_reason_code LIKE '%OUT%'|| message_reason_code LIKE '%FAILED%' /*we can add date here*/ UNION ALL SELECT t2.transaction_pci_details_id, t2.terminal_id, t2.transaction_no, t2.transaction_id, t2.transaction_type, t2.reversal_flag, t2.transmission_date_time, t2.retrivel_ref_no, t2.card_no, t2.card_type, t2.expires_on, t2.transaction_amount, t2.currency_code, t2.response_code, t2.action_code, t2.message_reason_code, t2.merchant_id, t2.auth_code, t2.actual_trans_amnt, t2.bal_card_amnt FROM ( SELECT transaction_id FROM TRANSACTION WHERE transaction_type_id = 8 ) AS t1 INNER JOIN ( SELECT * FROM transaction_pci_details WHERE message_reason_code LIKE '%appro%' /*we can add date here*/ ) AS t2 ON t1.transaction_id = t2.transaction_id ) AS t3 INNER JOIN ( SELECT* FROM transaction_pci_details WHERE action_code LIKE '%REQ%' /*we can add date here*/ ) AS t4 ON t3.transaction_pci_details_id - t4.transaction_pci_details_id = 1 ) AS t6 ON t5.transaction_id = t6.transaction_id

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  • Error 404 after rewrite query strings with htaccess

    - by Cristian
    I'm trying to redirect the URLs of a client's website like this: www.localsite.com/immobile.php?id_immobile=24 In something like this: www.localsite.com/immobile/24.php I'm using this rule in .htaccess but it returns a 404 error page. RewriteEngine On RewriteCond %{QUERY_STRING} ^id_immobile=([0-9]*)$ RewriteRule ^immobile\.php$ http://localsite.com/immobile/%1.php? [L] I have tried many other rules, but none work. What can I do?

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  • Sub query pass through

    - by SQL and the like
    Occasionally in forums and on client sites I see conditional subqueries in statements. This is where the developer has decided that it is only necessary to process some data under a certain condition.  By way of example, something like this : Create Procedure GetOrder @SalesOrderId integer, @CountDetails tinyint as Select SOH.salesorderid , case when @CountDetails = 1 then (Select count(*) from Sales.SalesOrderDetail SOD where SOH.SalesOrderID = SOD.SalesOrderID) end from sales.SalesOrderHeader...(read more)

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  • Understanding Regular Expressions (focus on URL Rewrite)–Part 11 (Sub-Part 2 of 2)

    - by OWScott
    This 2nd part (out of 2) on Regular Expressions covers the remaining tips necessary to get up to speed on a topic that at first seems daunting, but really isn’t that bad. Whether you use Regular Expressions for URL Rewrite, Visual Studio, PowerShell, programming or any other tool, these tips will allow you to understand the essentials of Regular Expressions. Be sure to watch Part 1 first. This is week 11 of a 52 week series on various web administration related tasks. Past and future videos can be found here.

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  • Visual Studio 2010 Find and Replace With Regular Expressions

    - by Lance Robinson
    Here is a quick notes about using regular expressions in the VS2010 Find Replace dialog.  1.  To create a backreference, use curly braces (“{“ and “}” ) instead of regular parentheses. 2.  To use the captured backreference, use \1\2 etc, where \1 is the first captured value, \2 is the second captured value, etc. Example: I want to find*: info.setFieldValue(param1, param2); and replace it with: SetFieldValue(info, param1, param2); To do this, I can use the following find/replace values: Find what: {[a-zA-Z0-9]+}.setFieldValue\({[a-zA-Z0-9., ]+}\); Replace with: SetFieldValue(\1, \2); Use Regular Expressions is checked, of course. *If you’re wondering why I’d want to do this – because I don’t have control over the setFieldValue function – its in a third party library that doesn’t behave in a very friendly manner. Technorati Tags: Visual Studio,Regular Expressions

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  • Executing a modified expression

    - by Sam
    I found this brief demo: http://msdn.microsoft.com/en-us/library/bb546136.aspx Which discusses modifying an expression. However the code starts with a Expression<Func<string, bool>> and ends up with a Expression so it's not complete. How do I take that expression and make it typed as Expression<Func<string,bool>> again? All the examples I have have found on executing an expression all involve dynamically created expressions which is not what this case has. Here the original expression is defined at compile time. And the code I want to write to do this won't know much about the expression, ideally as little as possible. I definately can't see how I would know what "Paramaters" to pass to Expression.LambdaExpression... In my particular case I want to search for any references to a particular propery of type A and swap them out with a reference to a property of type B then pass the expression to a call to IEnumerable.Where. ie. p=>p.Name == "Sam" where P is Foo1 becomes p=>p.FirstName == "Sam" where p is Foo2

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  • An abundance of LINQ queries and expressions using both the query and method syntax.

    - by nikolaosk
    In this post I will be writing LINQ queries against an array of strings, an array of integers.Moreover I will be using LINQ to query an SQL Server database. I can use LINQ against arrays since the array of strings/integers implement the IENumerable interface. I thought it would be a good idea to use both the method syntax and the query syntax. There are other places on the net where you can find examples of LINQ queries but I decided to create a big post using as many LINQ examples as possible. We...(read more)

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  • Regular Expressions Reference Tables Updated

    - by Jan Goyvaerts
    The regular expressions reference on the Regular-Expressions.info website was completely overhauled with the big update of that site last month. In the past, the reference section consisted of two parts. One part was a summary of the regex features commonly found in Perl-style regex flavors with short descriptions and examples. This part of the reference ignored differences between regex flavors and omitted most features that don’t have wide support. The other part was a regular expression flavor comparison that listed many more regex features along with YES/no indicators for many regex flavors, but without any explanations of the features. When reworking the site, I wanted to make the reference section more detailed, with descriptions and examples of all the syntax supported by the flavors discussed on the site. Doing that resulted in a reference that lists many features that are only supported by a few regex flavors. For such a reference to be usable, it needs to indicate which flavors support each feature. My original design for the new reference table used two rows for each feature. The first row had 4 columns with a label, syntax, description, and example, similar to the old reference tables. The second row had 20 columns indicating which versions of which flavors support these features. While the double-row design allowed all the information to fit within the table without requiring horizontal scrolling, it made it more difficult to quickly scan the tables for the feature you’re looking for. To make the new reference tables easier to read, they now have only a single row for each feature. The first 4 columns are the same as before. The remaining two columns show which versions of two regular expression flavors support the feature. You can use the drop-down lists above the table to choose the flavors the table should indicate. The site uses cookies to allow the flavor choices to persist while you navigate the reference. The result of this latest update is that the new regex tables are now just as easy to read as the ten-year-old tables on the old site were, while still covering all the features big and small of all the flavors discussed on the site.

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  • Second Edition of Regular Expressions Cookbook Has Been Published

    - by Jan Goyvaerts
    %COOKBOOKFRAME% The first edition of Regular Expressions Cookbook was published in May of 2009. It quickly became a bestseller, briefly holding the #1 spot in computer books on Amazon.com. It also had staying power. The ebook version was O’Reilly’s top seller during the whole year of 2010. So it’s no surprise that our editor at O’Reilly soon contacted us for a second edition. With Steven and I always being very busy, those plans were delayed until finally both of us found the time to update the book. Work started in January. Today you can buy your own copy of the second edition of Regular Expressions Cookbook. O’Reilly’s online shop sells the eBook in DRM-free ePub, Mobi, and PDF formats for $39.99 and the print version for $49.99. These are the list prices for the eBook and the print book. If you’re looking for a discount and free shipping of the print book, you can pre-order on one of the various Amazon sites. Deliveries should start soon. The discount rates differ and are subject to change. Amazon will also pay me an affiliate commission if you use one of these links, which pretty much doubles the income I get from the book. Amazon.com. Free shipping to the USA. Amazon.co.uk. Free shipping to the UK and Ireland. Amazon.fr. Free shipping to France, Monaco, Luxembourg, and Belgium. Amazon.de. Free shipping to Germany, Austria, Switzerland, Luxembourg, Liechtenstein, Belgium, and The Netherlands. If you don’t want to wait for the print book to arrive, the Kindle edition is already available for instant delivery. The Kindle edition works on Amazon’s Kindle hardware, and on PCs via Amazon’s Kindle software (free download). Amazon.com Amazon.co.uk Amazon.fr Amazon.de I’ll blog more about the book in the coming days and weeks with details about what’s new in the second edition.

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  • Second Edition of Regular Expressions Cookbook Now In Stock at Amazon.com

    - by Jan Goyvaerts
    %COOKBOOKFRAME% The second edition of Regular Expressions Cookbook is now in stock as a printed book Amazon.com. Right now, the printed book is discounted 45% to $27.51, which is actually more than a dollar cheaper than the Kindle edition. The European Amazon sites don’t have the printed book in stock yet. But it shouldn’t take too long for the book to make it from the US to Europe. They do have the Kindle edition.

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  • Does the order of columns in a query matter?

    - by James Simpson
    When selecting columns from a MySQL table, is performance affected by the order that you select the columns as compared to their order in the table (not considering indexes that may cover the columns)? For example, you have a table with rows uid, name, bday, and you have the following query. SELECT uid, name, bday FROM table Does MySQL see the following query any differently and thus cause any sort of performance hit? SELECT uid, bday, name FROM table

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  • Regular Expressions Cookbook Is in The Money—Win a Copy

    - by Jan Goyvaerts
    %COOKBOOKFRAME%You may have heard some people say that most book authors never get any royalties. That’s not true because most authors get an advance royalty that is paid before the book is published. That’s the author’s main incentive for writing the book, at least as far as money is concerned. (If money is your main concern, don’t write books.) What is true is that most authors never see any money beyond the advance royalty. Royalty rates are very low. A 10% royalty of the publisher’s price is considered normal. The publisher’s price is usually 45% of the retail price. So if you pay full price in a bookstore, the author gets 4.5% of your money. If there’s more than one author, they split the royalty. It doesn’t take a math degree to figure out that a book needs to sell quite a few copies for the royalty to add up to a meaningful amount of money. But Steven and I must have done something right. Regular Expressions Cookbook is in the money. My royalty statement for the 3rd quartier of 2009, which is the 2nd quarter that the book was on the market, came with a check. I actually received it last month but didn’t get around to blogging about. The amount of the check is insignificant. The point is that the balance is no longer negative. I’m taking this opportunity to pat myself and my co-author on the back. To celebrate the occassion O’Reilly has offered to sponsor a give-away of five (5) copies of Regular Expressions Cookbook. These are the rules of the game: You must post a comment to this blog article including your actual name and actual email address. Names are published, email addresses are not. Comments are moderated by myself (Jan Goyvaerts). If I consider a comment to be offensive or spam it will not be published and not be eligible for any prize. If you don’t know what to say in the comment, just wish me a happy 100000nd birthday, so I don’t have to feel so bad about entering the 6-bit era. Each person commenting has only one chance to win, regardless of the number of comments posted. O’Reilly will be provided with the names and email addresses of the winners (and those email addresses only) in order to arrange delivery. Each winner can choose to receive a printed copy or ebook (DRM-free PDF). If you choose the printed book, O’Reilly pays for shipping to anywhere in the world but not for any duties or taxes your country may impose on books imported from the USA. If you choose the ebook, you’ll need to create an O’Reilly account that is then granted access to the PDF download. You can make your choice after you’ve won, so it doesn’t influence your chance of winning. Contest ends 28 February 2010, GMT+7 (Thai time). Chosen by five calls to Random(78)+1 in Delphi 2010, the winners are: 48: Xiaozu 45: David Chisholm 19: Miquel Burns 33: Aaron Rice 17: David Laing Thanks to everybody who participated. The winners have been notified by email on how to collect their prize.

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  • Article : les expressions régulières revisitées, clair et exhaustif, tout ce qu'il vous faut pour le

    Bonsoir, Cette discussion est consacrée à l'article sur les expressions régulières. Cet article présente le fonctionnement des expressions régulières, la syntaxe et l'utilisation de cet outil avec .Net. http://stormimon.developpez.com/dotn...ns-regulieres/ N'hésitez pas à poster vos commentaires et remarques concernant l'article afin de m'aider à l'améliorer. Bonne lecture ...

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  • Problem with JMX query of Coherence node MBeans visible in JConsole

    - by Quinn Taylor
    I'm using JMX to build a custom tool for monitoring remote Coherence clusters at work. I'm able to connect just fine and query MBeans directly, and I've acquired nearly all the information I need. However, I've run into a snag when trying to query MBeans for specific caches within a cluster, which is where I can find stats about total number of gets/puts, average time for each, etc. The MBeans I'm trying to access programatically are visible when I connect to the remote process using JConsole, and have names like this: Coherence:type=Cache,service=SequenceQueue,name=SEQ%GENERATOR,nodeId=1,tier=back It would make it more flexible if I can dynamically grab all type=Cache MBeans for a particular node ID without specifying all the caches. I'm trying to query them like this: QueryExp specifiedNodeId = Query.eq(Query.attr("nodeId"), Query.value(nodeId)); QueryExp typeIsCache = Query.eq(Query.attr("type"), Query.value("Cache")); QueryExp cacheNodes = Query.and(specifiedNodeId, typeIsCache); ObjectName coherence = new ObjectName("Coherence:*"); Set<ObjectName> cacheMBeans = mBeanServer.queryMBeans(coherence, cacheNodes); However, regardless of whether I use queryMBeans() or queryNames(), the query returns a Set containing... ...0 objects if I pass the arguments shown above ...0 objects if I pass null for the first argument ...all MBeans in the Coherence:* domain (112) if I pass null for the second argument ...every single MBean (128) if I pass null for both arguments The first two results are the unexpected ones, and suggest a problem in the QueryExp I'm passing, but I can't figure out what the problem is. I even tried just passing typeIsCache or specifiedNodeId for the second parameter (with either coherence or null as the first parameter) and I always get 0 results. I'm pretty green with JMX — any insight on what the problem is? (FYI, the monitoring tool will be run on Java 5, so things like JMX 2.0 won't help me at this point.)

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  • MySQL select query result set changes based on column order

    - by user197191
    I have a drupal 7 site using the Views module to back-end site content search results. The same query with the same dataset returns different results from MySQL 5.5.28 to MySQL 5.6.14. The results from 5.5.28 are the correct, expected results. The results from 5.6.14 are not. If, however, I simply move a column in the select statement, the query returns the correct results. Here is the code-generated query in question (modified for readability). I apologize for the length; I couldn't find a way to reproduce it without the whole query: SELECT DISTINCT node_node_revision.nid AS node_node_revision_nid, node_revision.title AS node_revision_title, node_field_revision_field_position_institution_ref.nid AS node_field_revision_field_position_institution_ref_nid, node_revision.vid AS vid, node_revision.nid AS node_revision_nid, node_node_revision.title AS node_node_revision_title, SUM(search_index.score * search_total.count) AS score, 'node' AS field_data_field_system_inst_name_node_entity_type, 'node' AS field_revision_field_position_college_division_node_entity_t, 'node' AS field_revision_field_position_department_node_entity_type, 'node' AS field_revision_field_search_lvl_degree_lvls_node_entity_type, 'node' AS field_revision_field_position_app_deadline_node_entity_type, 'node' AS field_revision_field_position_start_date_node_entity_type, 'node' AS field_revision_body_node_entity_type FROM node_revision node_revision LEFT JOIN node node_node_revision ON node_revision.nid = node_node_revision.nid LEFT JOIN field_revision_field_position_institution_ref field_revision_field_position_institution_ref ON node_revision.vid = field_revision_field_position_institution_ref.revision_id AND (field_revision_field_position_institution_ref.entity_type = 'node' AND field_revision_field_position_institution_ref.deleted = '0') LEFT JOIN node node_field_revision_field_position_institution_ref ON field_revision_field_position_institution_ref.field_position_institution_ref_target_id = node_field_revision_field_position_institution_ref.nid LEFT JOIN field_revision_field_position_cip_code field_revision_field_position_cip_code ON node_revision.vid = field_revision_field_position_cip_code.revision_id AND (field_revision_field_position_cip_code.entity_type = 'node' AND field_revision_field_position_cip_code.deleted = '0') LEFT JOIN node node_field_revision_field_position_cip_code ON field_revision_field_position_cip_code.field_position_cip_code_target_id = node_field_revision_field_position_cip_code.nid LEFT JOIN node node_node_revision_1 ON node_revision.nid = node_node_revision_1.nid LEFT JOIN field_revision_field_position_vacancy_status field_revision_field_position_vacancy_status ON node_revision.vid = field_revision_field_position_vacancy_status.revision_id AND (field_revision_field_position_vacancy_status.entity_type = 'node' AND field_revision_field_position_vacancy_status.deleted = '0') LEFT JOIN search_index search_index ON node_revision.nid = search_index.sid LEFT JOIN search_total search_total ON search_index.word = search_total.word WHERE ( ( (node_node_revision.status = '1') AND (node_node_revision.type IN ('position')) AND (field_revision_field_position_vacancy_status.field_position_vacancy_status_target_id IN ('38')) AND( (search_index.type = 'node') AND( (search_index.word = 'accountant') ) ) AND ( (node_revision.vid=node_node_revision.vid AND node_node_revision.status=1) ) ) ) GROUP BY search_index.sid, vid, score, field_data_field_system_inst_name_node_entity_type, field_revision_field_position_college_division_node_entity_t, field_revision_field_position_department_node_entity_type, field_revision_field_search_lvl_degree_lvls_node_entity_type, field_revision_field_position_app_deadline_node_entity_type, field_revision_field_position_start_date_node_entity_type, field_revision_body_node_entity_type HAVING ( ( (COUNT(*) >= '1') ) ) ORDER BY node_node_revision_title ASC LIMIT 20 OFFSET 0; Again, this query returns different sets of results from MySQL 5.5.28 (correct) to 5.6.14 (incorrect). If I move the column named "score" (the SUM() column) to the end of the column list, the query returns the correct set of results in both versions of MySQL. My question is: Is this expected behavior (and why), or is this a bug? I'm on the verge of reverting my entire environment back to 5.5 because of this.

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  • In MySQL, what is the most effective query design for joining large tables with many to many relatio

    - by lighthouse65
    In our application, we collect data on automotive engine performance -- basically source data on engine performance based on the engine type, the vehicle running it and the engine design. Currently, the basis for new row inserts is an engine on-off period; we monitor performance variables based on a change in engine state from active to inactive and vice versa. The related engineState table looks like this: +---------+-----------+---------------+---------------------+---------------------+-----------------+ | vehicle | engine | engine_state | state_start_time | state_end_time | engine_variable | +---------+-----------+---------------+---------------------+---------------------+-----------------+ | 080025 | E01 | active | 2008-01-24 16:19:15 | 2008-01-24 16:24:45 | 720 | | 080028 | E02 | inactive | 2008-01-24 16:19:25 | 2008-01-24 16:22:17 | 304 | +---------+-----------+---------------+---------------------+---------------------+-----------------+ For a specific analysis, we would like to analyze table content based on a row granularity of minutes, rather than the current basis of active / inactive engine state. For this, we are thinking of creating a simple productionMinute table with a row for each minute in the period we are analyzing and joining the productionMinute and engineEvent tables on the date-time columns in each table. So if our period of analysis is from 2009-12-01 to 2010-02-28, we would create a new table with 129,600 rows, one for each minute of each day for that three-month period. The first few rows of the productionMinute table: +---------------------+ | production_minute | +---------------------+ | 2009-12-01 00:00 | | 2009-12-01 00:01 | | 2009-12-01 00:02 | | 2009-12-01 00:03 | +---------------------+ The join between the tables would be engineState AS es LEFT JOIN productionMinute AS pm ON es.state_start_time <= pm.production_minute AND pm.production_minute <= es.event_end_time. This join, however, brings up multiple environmental issues: The engineState table has 5 million rows and the productionMinute table has 130,000 rows When an engineState row spans more than one minute (i.e. the difference between es.state_start_time and es.state_end_time is greater than one minute), as is the case in the example above, there are multiple productionMinute table rows that join to a single engineState table row When there is more than one engine in operation during any given minute, also as per the example above, multiple engineState table rows join to a single productionMinute row In testing our logic and using only a small table extract (one day rather than 3 months, for the productionMinute table) the query takes over an hour to generate. In researching this item in order to improve performance so that it would be feasible to query three months of data, our thoughts were to create a temporary table from the engineEvent one, eliminating any table data that is not critical for the analysis, and joining the temporary table to the productionMinute table. We are also planning on experimenting with different joins -- specifically an inner join -- to see if that would improve performance. What is the best query design for joining tables with the many:many relationship between the join predicates as outlined above? What is the best join type (left / right, inner)?

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  • SQL SERVER – Signal Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Signal Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Signal Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Signal Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the Signalwait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the Signal wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the Signal wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Single Wait Time Introduction with Simple Example – Wait Type – Day 2 of 28

    - by pinaldave
    In this post, let’s delve a bit more in depth regarding wait stats. The very first question: when do the wait stats occur? Here is the simple answer. When SQL Server is executing any task, and if for any reason it has to wait for resources to execute the task, this wait is recorded by SQL Server with the reason for the delay. Later on we can analyze these wait stats to understand the reason the task was delayed and maybe we can eliminate the wait for SQL Server. It is not always possible to remove the wait type 100%, but there are few suggestions that can help. Before we continue learning about wait types and wait stats, we need to understand three important milestones of the query life-cycle. Running - a query which is being executed on a CPU is called a running query. This query is responsible for CPU time. Runnable – a query which is ready to execute and waiting for its turn to run is called a runnable query. This query is responsible for Single Wait time. (In other words, the query is ready to run but CPU is servicing another query). Suspended – a query which is waiting due to any reason (to know the reason, we are learning wait stats) to be converted to runnable is suspended query. This query is responsible for wait time. (In other words, this is the time we are trying to reduce). In simple words, query execution time is a summation of the query Executing CPU Time (Running) + Query Wait Time (Suspended) + Query Single Wait Time (Runnable). Again, it may be possible a query goes to all these stats multiple times. Let us try to understand the whole thing with a simple analogy of a taxi and a passenger. Two friends, Tom and Danny, go to the mall together. When they leave the mall, they decide to take a taxi. Tom and Danny both stand in the line waiting for their turn to get into the taxi. This is the Signal Wait Time as they are ready to get into the taxi but the taxis are currently serving other customer and they have to wait for their turn. In other word they are in a runnable state. Now when it is their turn to get into the taxi, the taxi driver informs them he does not take credit cards and only cash is accepted. Neither Tom nor Danny have enough cash, they both cannot get into the vehicle. Tom waits outside in the queue and Danny goes to ATM to fetch the cash. During this time the taxi cannot wait, they have to let other passengers get into the taxi. As Tom and Danny both are outside in the queue, this is the Query Wait Time and they are in the suspended state. They cannot do anything till they get the cash. Once Danny gets the cash, they are both standing in the line again, creating one more Single Wait Time. This time when their turn comes they can pay the taxi driver in cash and reach their destination. The time taken for the taxi to get from the mall to the destination is running time (CPU time) and the taxi is running. I hope this analogy is bit clear with the wait stats. You can check the single wait stats using following query of Glenn Berry. -- Signal Waits for instance SELECT CAST(100.0 * SUM(signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%signal (cpu) waits], CAST(100.0 * SUM(wait_time_ms - signal_wait_time_ms) / SUM (wait_time_ms) AS NUMERIC(20,2)) AS [%resource waits] FROM sys.dm_os_wait_stats OPTION (RECOMPILE); Higher the single wait stats are not good for the system. Very high value indicates CPU pressure. In my experience, when systems are running smooth and without any glitch the single wait stat is lower than 20%. Again, this number can be debated (and it is from my experience and is not documented anywhere). In other words, lower is better and higher is not good for the system. In future articles we will discuss in detail the various wait types and wait stats and their resolution. Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL DMV, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Query returns too few rows

    - by Tareq
    setup: mysql> create table product_stock( product_id integer, qty integer, branch_id integer); Query OK, 0 rows affected (0.17 sec) mysql> create table product( product_id integer, product_name varchar(255)); Query OK, 0 rows affected (0.11 sec) mysql> insert into product(product_id, product_name) values(1, 'Apsana White DX Pencil'); Query OK, 1 row affected (0.05 sec) mysql> insert into product(product_id, product_name) values(2, 'Diamond Glass Marking Pencil'); Query OK, 1 row affected (0.03 sec) mysql> insert into product(product_id, product_name) values(3, 'Apsana Black Pencil'); Query OK, 1 row affected (0.03 sec) mysql> insert into product_stock(product_id, qty, branch_id) values(1, 100, 1); Query OK, 1 row affected (0.03 sec) mysql> insert into product_stock(product_id, qty, branch_id) values(1, 50, 2); Query OK, 1 row affected (0.03 sec) mysql> insert into product_stock(product_id, qty, branch_id) values(2, 80, 1); Query OK, 1 row affected (0.03 sec) my query: mysql> SELECT IFNULL(SUM(s.qty),0) AS stock, product_name FROM product_stock s RIGHT JOIN product p ON s.product_id=p.product_id WHERE branch_id=1 GROUP BY product_name ORDER BY product_name; returns: +-------+-------------------------------+ | stock | product_name | +-------+-------------------------------+ | 100 | Apsana White DX Pencil | | 80 | Diamond Glass Marking Pencil | +-------+-------------------------------+ 1 row in set (0.00 sec) But I want to have the following result: +-------+------------------------------+ | stock | product_name | +-------+------------------------------+ | 0 | Apsana Black Pencil | | 100 | Apsana White DX Pencil | | 80 | Diamond Glass Marking Pencil | +-------+------------------------------+ To get this result what mysql query should I run?

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  • How do I filter one of the columns in a SQL Server SQL Query

    - by Kent S. Clarkson
    I have a table (that relates to a number of other tables) where I would like to filter ONE of the columns (RequesterID) - that column will be a combobox where only people that are not sales people should be selectable. Here is the "unfiltered" query, lets call it QUERY 1: SELECT RequestsID, RequesterID, ProductsID FROM dbo.Requests If using a separate query, lets call it QUERY 2, to filter RequesterID (which is a People related column, connected to People.PeopleID), it would look like this: SELECT People.PeopleID FROM People INNER JOIN Roles ON People.RolesID = Roles.RolesID INNER JOIN Requests ON People.PeopleID = Requests.RequesterID WHERE (Roles.Role <> N'SalesGuy') ORDER BY Requests.RequestsID Now, is there a way of "merging" the QUERY 2 into QUERY 1? (dbo.Requests in QUERY 1 has RequesterID populated as a Foreign Key from dbo.People, so no problem there... The connections are all right, just not know how to write the SQL query!)

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